Warn users when addresses in ports and descriptor are inconsistent

This mitigates bug 13953.

changes/bug13953

@@ -0,0 +1,3 @@
+  o Minor bugfixes (config):
+    - Warn users when descriptor and port addresses are inconsistent.
+      Mitigates bug 13953; patch by teor.

src/or/config.c

@@ -7037,6 +7037,87 @@ get_first_advertised_port_by_type_af(int listener_type, int address_family)
   return 0;
 }
 
+/** Return the first advertised address of type <b>listener_type</b> in
+ * <b>address_family</b>. Returns NULL if there is no advertised address,
+ * and when passed AF_UNSPEC. */
+const tor_addr_t *
+get_first_advertised_addr_by_type_af(int listener_type, int address_family)
+{
+  if (address_family == AF_UNSPEC)
+    return NULL;
+  if (!configured_ports)
+    return NULL;
+  SMARTLIST_FOREACH_BEGIN(configured_ports, const port_cfg_t *, cfg) {
+    if (cfg->type == listener_type &&
+        !cfg->server_cfg.no_advertise) {
+      if ((address_family == AF_INET && port_binds_ipv4(cfg)) ||
+          (address_family == AF_INET6 && port_binds_ipv6(cfg))) {
+        return &cfg->addr;
+      }
+    }
+  } SMARTLIST_FOREACH_END(cfg);
+  return NULL;
+}
+
+/** Return 1 if a port exists of type <b>listener_type</b> on <b>addr</b> and
+ * <b>port</b>. If <b>check_wildcard</b> is true, INADDR[6]_ANY and AF_UNSPEC
+ * addresses match any address of the appropriate family; and port -1 matches
+ * any port.
+ * To match auto ports, pass CFG_PORT_AUTO. (Does not match on the actual
+ * automatically chosen listener ports.) */
+int
+port_exists_by_type_addr_port(int listener_type, const tor_addr_t *addr,
+                              int port, int check_wildcard)
+{
+  if (!configured_ports || !addr)
+    return 0;
+  SMARTLIST_FOREACH_BEGIN(configured_ports, const port_cfg_t *, cfg) {
+    if (cfg->type == listener_type) {
+      if (cfg->port == port || (check_wildcard && port == -1)) {
+        /* Exact match */
+        if (tor_addr_eq(&cfg->addr, addr)) {
+          return 1;
+        }
+        /* Skip wildcard matches if we're not doing them */
+        if (!check_wildcard) {
+          continue;
+        }
+        /* Wildcard matches IPv4 */
+        const int cfg_v4 = port_binds_ipv4(cfg);
+        const int cfg_any_v4 = tor_addr_is_null(&cfg->addr) && cfg_v4;
+        const int addr_v4 = tor_addr_family(addr) == AF_INET ||
+                            tor_addr_family(addr) == AF_UNSPEC;
+        const int addr_any_v4 = tor_addr_is_null(&cfg->addr) && addr_v4;
+        if ((cfg_any_v4 && addr_v4) || (cfg_v4 && addr_any_v4)) {
+          return 1;
+        }
+        /* Wildcard matches IPv6 */
+        const int cfg_v6 = port_binds_ipv6(cfg);
+        const int cfg_any_v6 = tor_addr_is_null(&cfg->addr) && cfg_v6;
+        const int addr_v6 = tor_addr_family(addr) == AF_INET6 ||
+                            tor_addr_family(addr) == AF_UNSPEC;
+        const int addr_any_v6 = tor_addr_is_null(&cfg->addr) && addr_v6;
+        if ((cfg_any_v6 && addr_v6) || (cfg_v6 && addr_any_v6)) {
+          return 1;
+        }
+      }
+    }
+  } SMARTLIST_FOREACH_END(cfg);
+  return 0;
+}
+
+/* Like port_exists_by_type_addr_port, but accepts a host-order IPv4 address
+ * instead. */
+int
+port_exists_by_type_addr32h_port(int listener_type, uint32_t addr_ipv4h,
+                                 int port, int check_wildcard)
+{
+  tor_addr_t ipv4;
+  tor_addr_from_ipv4h(&ipv4, addr_ipv4h);
+  return port_exists_by_type_addr_port(listener_type, &ipv4, port,
+                                       check_wildcard);
+}
+
 /** Adjust the value of options->DataDirectory, or fill it in if it's
  * absent. Return 0 on success, -1 on failure. */
 static int

src/or/config.h

@@ -87,6 +87,12 @@ int get_first_advertised_port_by_type_af(int listener_type,
   (get_first_advertised_port_by_type_af(CONN_TYPE_OR_LISTENER, AF_INET))
 #define get_primary_dir_port() \
   (get_first_advertised_port_by_type_af(CONN_TYPE_DIR_LISTENER, AF_INET))
+const tor_addr_t *get_first_advertised_addr_by_type_af(int listener_type,
+                                                       int address_family);
+int port_exists_by_type_addr_port(int listener_type, const tor_addr_t *addr,
+                                  int port, int check_wildcard);
+int port_exists_by_type_addr32h_port(int listener_type, uint32_t addr_ipv4h,
+                                     int port, int check_wildcard);
 
 char *get_first_listener_addrport_string(int listener_type);
 

src/or/router.c

@@ -1896,6 +1896,85 @@ router_pick_published_address,(const or_options_t *options, uint32_t *addr))
   return 0;
 }
 
+/* Tor relays only have one IPv4 address in the descriptor, which is derived
+ * from the Address torrc option, or guessed using various methods in
+ * router_pick_published_address().
+ * Warn the operator if there is no ORPort on the descriptor address
+ * ipv4h_desc_addr.
+ * Warn the operator if there is no DirPort on the descriptor address.
+ * This catches a few common config errors:
+ *  - operators who expect ORPorts and DirPorts to be advertised on the
+ *    ports' listen addresses, rather than the torrc Address (or guessed
+ *    addresses in the absence of an Address config). This includes
+ *    operators who attempt to put their ORPort and DirPort on different
+ *    addresses;
+ *  - discrepancies between guessed addresses and configured listen
+ *    addresses (when the Address option isn't set).
+ * If a listener is listening on all IPv4 addresses, it is assumed that it
+ * is listening on the configured Address, and no messages are logged.
+ * If an operators has specified NoAdvertise ORPorts in a NAT setting,
+ * no messages are logged, unless they have specified other advertised
+ * addresses.
+ * The message tells operators to configure an ORPort and DirPort that match
+ * the Address (using NoListen if needed).
+ */
+static void
+router_check_descriptor_address_consistency(uint32_t ipv4h_desc_addr)
+{
+
+  /* The first configured ORPort and DirPort, which may be CFG_AUTO_PORT. */
+  int orport_v4_cfg = get_first_advertised_port_by_type_af(
+                                                        CONN_TYPE_OR_LISTENER,
+                                                        AF_INET);
+  int dirport_v4_cfg = get_first_advertised_port_by_type_af(
+                                                        CONN_TYPE_DIR_LISTENER,
+                                                        AF_INET);
+
+  if (orport_v4_cfg != 0 &&
+      !port_exists_by_type_addr32h_port(CONN_TYPE_OR_LISTENER,
+                                        ipv4h_desc_addr, orport_v4_cfg, 1)) {
+      const tor_addr_t *port_addr = get_first_advertised_addr_by_type_af(
+                                                        CONN_TYPE_OR_LISTENER,
+                                                        AF_INET);
+      tor_addr_t desc_addr;
+      char port_addr_str[TOR_ADDR_BUF_LEN];
+      char desc_addr_str[TOR_ADDR_BUF_LEN];
+
+      tor_addr_to_str(port_addr_str, port_addr, TOR_ADDR_BUF_LEN, 0);
+
+      tor_addr_from_ipv4h(&desc_addr, ipv4h_desc_addr);
+      tor_addr_to_str(desc_addr_str, &desc_addr, TOR_ADDR_BUF_LEN, 0);
+
+      log_warn(LD_CONFIG, "The configured IPv4 ORPort address %s does not "
+               "match the address %s in the descriptor. Please configure "
+               "matching IPv4 addresses for the Address and ORPort options. "
+               "Use NoListen on the ORPort if you are behind a NAT.",
+               port_addr_str, desc_addr_str);
+    }
+
+  if (dirport_v4_cfg != 0 &&
+      !port_exists_by_type_addr32h_port(CONN_TYPE_DIR_LISTENER,
+                                        ipv4h_desc_addr, dirport_v4_cfg, 1)) {
+      const tor_addr_t *port_addr = get_first_advertised_addr_by_type_af(
+                                                        CONN_TYPE_DIR_LISTENER,
+                                                        AF_INET);
+      tor_addr_t desc_addr;
+      char port_addr_str[TOR_ADDR_BUF_LEN];
+      char desc_addr_str[TOR_ADDR_BUF_LEN];
+
+      tor_addr_to_str(port_addr_str, port_addr, TOR_ADDR_BUF_LEN, 0);
+
+      tor_addr_from_ipv4h(&desc_addr, ipv4h_desc_addr);
+      tor_addr_to_str(desc_addr_str, &desc_addr, TOR_ADDR_BUF_LEN, 0);
+
+      log_warn(LD_CONFIG, "The configured IPv4 DirPort address %s does not "
+               "match the address %s in the descriptor. Please configure "
+               "matching IPv4 addresses for the Address and DirPort options. "
+               "Use NoListen on the DirPort if you are behind a NAT.",
+               port_addr_str, desc_addr_str);
+    }
+}
+
 /** Build a fresh routerinfo, signed server descriptor, and extra-info document
  * for this OR. Set r to the generated routerinfo, e to the generated
  * extra-info document. Return 0 on success, -1 on temporary error. Failure to
@@ -1918,6 +1997,10 @@ router_build_fresh_descriptor(routerinfo_t **r, extrainfo_t **e)
     return -1;
   }
 
+  /* Log a message if the address in the descriptor doesn't match the ORPort
+   * and DirPort addresses configured by the operator. */
+  router_check_descriptor_address_consistency(addr);
+
   ri = tor_malloc_zero(sizeof(routerinfo_t));
   ri->cache_info.routerlist_index = -1;
   ri->nickname = tor_strdup(options->Nickname);